#include <stdio.h>
int main()
 { 
    int a, s,n ,count ;
a=2 ,s=0 , n=1 ,count=1;
 while(count<=7)
 { n = n * 2;
   s = s + n ;
   count++;
 } 
printf("s = %d\n",s );
return 0;
}